To satisfy demands for wireless data traffic having increased since commercialization of 4th-Generation (4G) communication systems, efforts have been made to develop improved 5th-Generation (5G) communication systems or pre-5G communication systems. For this reason, the 5G communication system or the pre-5G communication system is also called a beyond-4G-network communication system or a post-long term evolution (LTE) system.
To achieve a high data rate, implementation of the 5G communication system in an ultra-high frequency (mmWave) band (e.g., a 60 GHz band) is under consideration. In the 5G communication system, beamforming, massive multi-input multi-output (MIMO), full dimensional MIMO (FD-MIMO), an array antenna, analog beamforming, and large-scale antenna technologies have been discussed to alleviate a propagation path loss and to increase a propagation distance in the ultra-high frequency band.
For system network improvement, in the 5G communication system, techniques such as an evolved small cell, an advanced small cell, a cloud radio access network (RAN), an ultra-dense network, device to device (D2D) communication, a wireless backhaul, a moving network, cooperative communication, coordinated multi-points (CoMPs), and interference cancellation have been developed.
In the 5G system, advanced coding modulation (ACM) schemes including hybrid frequency-shift keying (FSK) and quadrature amplitude modulation (QAM) modulation (FQAM) and sliding window superposition coding (SWSC), and advanced access schemes including filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) have been developed.
Meanwhile, most Internet services use, as a transmission protocol, a transmission control protocol (TCP) which is an end-to-end protocol and performs window-based transmission control for data transmission. That is, a TCP sender may transmit data corresponding to a size of a window to a TCP receiver, and in particular, the amount of data transmitted to the receiver by the sender after TCP session setup is based on a size of an initial window.
Since the TCP has been designed for use in a low-speed wired network having a frequent packet drop, the TCP sender transmits a small amount of data in initial transmission to prevent a packet drop, and thereafter, a window size is increased to transmit a larger amount of data only in a good network state. The network state may be determined, for example, based on whether an ACK packet is received from the receiver in response to data transmitted by the sender. A current TCP sender, e.g., an Internet server mostly uses 4 KB as an initial window value, and even in a radical setting case, the initial window size is only 10 KB.
However, a wireless cellular network such as LTE has a lower packet drop probability and a much better transmission network quality than a wired network. Thus, even if a user equipment (UE) in an LTE network has an available high air throughput, the TCP sender uses a very small initial window that is set arbitrarily because of not knowing a radio channel state, resulting in initial transmission delay. In this way, larger performance degradation occurs for higher air throughput available to the UE.
The initial transmission delay incurs, for example, video initial play time delay, and causes user inconvenience. By contrast, when the TCP sender uses an initial window that is set to an arbitrary large value, buffer overflow and a packet drop are likely to occur because a network state and a radio channel state are not considered.
Therefore, it is important to set a proper initial window value in a radio channel state.
The above data is presented as background data only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.